Various pile fabrics in which the piles are made of extremely fine synthetic polymer fibers other than the acrylic polymer fibers are known. However, these types of conventional pile fabrics have disadvantages that the pile fibers are difficult to dye a brilliant, deep color, and it is difficult to make the pile layer completely cover a substratum fabric to the extent that the substratum fabric can not be seen through the pile layer. That is, in the conventional synthetic fiber pile fabrics, the pile fibers are made of a polyester or polyamide, which are difficult to dye a brilliant, deep color, and the pile fibers in the pile layer have a relatively low density, and therefore, the pile layer has a relatively light color. For the above-mentioned reasons, the drawbacks of the conventional synthetic fiber pile fabrics can not be eliminated by any improvements in the dyeing processes for the pile fibers.
The disadvantage that the substratum fabric is seen through the pile layer is a serious drawback of the conventional synthetic fiber pile fabrics, for example, suede-like synthetic leathers. In order to eliminate this disadvantage, attempts have been made to increase the degree of raising applied to the substratum fabric, so as to increase the density of the piles in the pile layer, or to cover the substratum with a resin layer applied thereto. However, the increase in the degree of raising causes the strength of the substratum fabric to be remarkably reduced, and such a reduction in strength results in a decrease in the commercial value of the resultant pile fabric.
Furthermore, in order to completely cover the substratum fabric, it is necessary to apply a large amount of the resin to the pile fabric. The large amount of resin applied to the pile fabric causes the pile fibers to be embedded in the resin layer so as to form a smooth resin surface on the fabric. The resultant fabric has a very poor draping property due to the high stiffness of the resin layer.
There are no synthetic fiber pile fabrics without the disadvantages mentioned above on the commercial market. Therefore, the commercial synthetic fiber pile fabrics in which the piles are made of a synthetic polymer other than the acrylic polymer, are quite different in appearance and feel from natural suede leather.
In order to eliminate the above-mentioned disadvantages, attempts have been made to use acrylic polymer fibers for forming the piles. However, the resultant acrylic polymer fiber pile fabric was found to be unsatisfactory due to an improper stiffness and coarse feel of the acrylic polymer fibers. Accordingly, it is desired that special acrylic polymer fibers or filaments having a proper softness or stiffness and no coarse feel are provided.
Generally, in the process for producing the artificial leather, a solution of an elastic polymer, for example, polyurethane, in a hydrophilic organic solvent, for example, N,N-dimethylformamide, is applied to a substratum fabric, and the solution impregnated in the substratum fabric is coagulated with a coagulating liquid, for example, water. However, it was found that when the substratum fabric contains acrylic polymer fibers, the solvent for the elastic polymer also dissolves the acrylic polymer fibers. Accordingly, it is necessary to provide a new method for applying the elastic polymer to the substratum fabric containing the acrylic polymer fibers or filaments.